Adjustable torque hydraulic actuator system



J. MERCIER Filed May 31, 1961 ADJUSTABLE TORQUE HYDRAULIC ACTUATOR SYSTEM FIG. 2

INVENYOR JEAN HER -IER By M I: M

A1709. usvs FIG} March 9, 1965 United States Patent 3,172,333 ADFU STABLE TORQUE HYDRAULIC ACTUATOR SYSTEM Jean Mercier, 1185 Park Ave., New York, N.Y. Filed May 31, 1961, Ser. No. 113,887

1 Claim. (Cl. 91167) This invention relates to the art of hydraulic actuators more particularly of the telescopic type.

It is among the objects of the invention to provide a hydraulic actuator which is relatively simple in construction, dependable in operation and which has a plurality of moving elements that can be independently controlled by a plurality of fluid pressures applied thereto.

According to the invention, the actuator comprises at least two separate chambers, one being slidably mounted in the other and defining a plunger which may be actuated by the introduction of fluid under pressure in said other chamber. A second plunger is slidably mounted in said first chamber and is also actuated by fiuid under pressure forced into said first chamber, the two chambers and the second plunger being axially aligned and forming a telescopic arrangement.

Another object of the invention is to provide a hydraulic system utilizing a plurality of actuators of the above type to provide for angular displacement of a member about an axis.

According to the invention, these objects are accomplished by the arrangement and combination of elements hereinafter described and more particularly recited in the claim.

This application is a continuation-in-part of co-pending application Serial No. 823,947, filed June 30, 1959, now Patent No. 3,009,322, issued November 21, 1961.

In the accompanying drawings in which are shown one or more of various possible embodiments of the several features of the invention,

FIG. 1 is a longitudinal sectional view of the telescopic actuator according to the invention, and

FIGS. 2 and 3 are diagrammatic views of systems utilizing telescopic actuators.

Referring now to the drawings, the actuator or jack shown in FIG. 1 comprises a cylinder 1 closed at one end as at 1' and having a cap at its other end through which slidably extends a smaller diameter cylinder 2. The end 2' of cylinder 2 in cylinder 1 is closed and the other end of cylinder 2 has a cap through which slidably extends a tubular member 3. Appropriate gaskets 4 and 5 provide a seal between cylinders 1 and 2 and between cylinder 2 and tubular member 3.

The cylinder 2 thus forms a plunger in cylinder 1 and the tubular member 3 forms a plunger in cylinder 2.

The space between the cylinder 1 and the plunger or cylinder 2 defines a chamber 6 into which fluid under pressure may be admitted through a port 7 located in the wall of cylinder 1. The space between the cylinderv 2 and the tubular member 3 defines a chamber 8, which is independent of chamber 6 and into which fluid under pressure may be admitted through a port 9 leading into the bore of tubular member 3.

Flow of fluid under pressure into chamber 6 tends to cause outward longitudinal displacement of cylinders 1 and 2 and flow of fluid under pressure into chamber 8 tends to cause outward longitudinal displacement of cylinder 2 and tubular member 3.

Assuming that the cylinder 1 is secured in fixed position, then fluid under pressure forced into chamber 8 would cause elongation of the assembly comprising cylinder 2 and member 3, while a fluid under pressure forced into the chamber 6 would force the assembly 2, 3 out- 3,172,333 Patented Mar. 9, 1965 wardly from cylinder 1. Such movements would occur regardless of the values of the two pressures.

A telescope apparatus has therefore been provided which is of extreme simplicity. The two chambers 6 and 8 of the jack operate independently of each other and can be controlled at will. If, for example, the two chambers 6 and 8 are supplied successively or simultaneously with substantially equal pressures, there will exist in the chamber 8 a pressure sufficient to elongate the assembly 2-3 with a given force and in chamber 6 a pressure capable of displacing the said assembly 2-3 toward a position corresponding to the complete extension of the apparatus, with a force greater than that bringing about the elongation of the said assembly 2-3 due to the fact that the diameter of the cylinder 2 is greater than that of the member 3.

The telescopic apparatus according to the invention finds a desirable application in hydraulic systems and particularly those operating on a ship rudder.

Referring to FIG. 2, a rudder shaft 10 is provided on which the swing bar 11 of the rudder is mounted in manner to present two arms 12 and 13 of different lengths. Two telescopic actuators or jacks A and B of the type shown in FIG. 1 are provided. The plunger 3a of jack A is connected at 18 to the end of the arm 12 of bar 11, which is of shorter length, and the plunger 3b of the jack B is connected at 19 to the arm 13, which is of greater length. The distances between the shaft 10 and each of the pivotal points 18 and 19 are illustratively selected in manner such as to bear a 1 to 2 ratio.

The cylinders 1a, 1b of jacks A and B are connected respectively to fixed pivotal mounts 20, 23.

The liquid under pressure admitted into chambers 8a and 8b of the jacks A, B comes from a pump 31 connected by a line 32 to the reservoir 33 and the liquid under pressure admitted into chambers 6a and 6b of the jacks comes from a pump 34 connected by a line 35 to the reservoir 33.

More specifically, the outlet of pump 31 is connected by line 36 to a three-way distributor 42 and by line 37 to port 9a of jack A. In addition, one of the ports of the distributor 42 is connected by line 38 to port 9b of jack B and the other port is connected by line 45 to reservoir 33.

Similarly, the outlet of the pump 34 is connected by line 39 to a three-way distributor 43 and by line 40 to port 7a of jack A. In addition, one of the ports of the distributor 43 is connected by line 41 to port 7b of jack B and the other port is connected by line 45 to reservoir 33.

By means of the distributor, the chambers 8b and 6b of jack B can be connected either to pumps 31 or 34 respectively, or to the reservoir 33. 47 in lines 36, 39 control communication between pump 31 and the chamber 8:; and between the pump 34 and the chamber 6a of the jack A. Finally, the pressure accumulators 48, 49 connected to the lines 36, 39 con stitute a reservoir of energy in case of need.

The operation of the hydraulic system shown in FIG. 2 is as follows:

With the distributor 43 and the valve 47 in a posi tion in which the chambers 6a and 6b of the jacks A and B are connected to reservoir 33, the valve 46 is opened and the distributor 42 positioned so that the fluid from pump 31 will flow through line 36 into lines 37 and 38, into the chamber 8a of jack A and into the chamber 8b of jack B. As a result, the plungers 2a and 2b, respectively, will be driven toward the bottoms of cylinders 1a and 1b of the jacks A and B, the fluid I in the chambers 61: and 6b flowing into reservoir 33.

The valves. 46,.

Assuming that there was chosen for the lever arms of the swing bar 11 a ratio of 1:2, and that each of the pressure sources 31 or 48 and 34 or 49 is capable of dis charging liquid at a pressure of 300 kg. per sq. em, if it is desired to pivot the swing bar 11 in one direction or the other, it is sufiicient to control the pressure admitted to the chamber Sb by the distributor 42, in such manner that this pressure attains a value either below or above equilibriurn pressure, which is about 150 kg. per sq. cm. in the example selected.

Thus, assuming the pressure in line 37 reacting against the end of cylinder 2a is 300 kg. per sq. cm. and the pressure in line 38 reacting against the end of cylinder 2b is 150 kg. per sq. cm., since the ratio of the lever arms 12, 11 illustratively is 1 to 2, the system will be in equilibrium with no rotation of swing bar or control member 11.

Thus, if it is desired to pivot the swing bar 11 in a clockwise direction, for example, the distributor 42 is set so that the pressure admitted to the chamber Sb of jack B exceeds the equilibrium value. As a result, a displacement is brought about of the plunger 3b toward the left and the shaft is rotated in a clockwise direction.

As soon as the swing bar 11 and shaft 10 has attained the desired position, the distributor 42 is actuated to cut ofi communication between the chamber 8!) of jack B and the pressure source 31, 48, thus stopping the extension of plunger 3b of jack B.

To control a rotary movement of swing bar 11 in a counter-clockwise direction, the distributor 42 in actuated in manner to diminish the pressure in chamber 3b so that the jack A will assume control and its plunger 3a will extend and plunger 3b will retract.

If, for any reason whatsoever, the chambers 8a and 8b are not supplied with pressure, it is sufficient in order to restore the normal operations described, to so actuate the distributor 42 that it connects the lines 37 and 38 to the reservoir 33; to open the valve 47 in order to place the chamber 6a of jack A in communication with the sources 34, 49 and to actuate the distributor 43 so that the pressure conveyed from the sources 34, 49 by line 41 to the chamber 6b of jack B is in equilibrium with the pressure in chamber 6a of jack A.

The control of the position of swing bar 11 when use is made of the pressure sources 34-49 occursin the same manner as the normal control in which there is utilized the pressure sources 31, 48, the only diflerence residing in the fact that the pressures admitted enter the chambers 6a and 6b and displace plungers 2a and 2b of jacks A and B against the plungers 3a and 3b. The plungers 2a, 2b and 3a, 3b thereupon are displaced in one direction or the other as previously described when there is admitted at 6b a pressure above or below half that which exists at 6a.

It is to be noted, however that the force exerted against plungers 2a and 2b is greater than that which could be exerted against plungers 3a and 3b in normal operation from the pressure sources 3148 (assuming that the two sources are under the same pressure).

Hence, with both sources of pressure operative, the cylinders 2a and 2b would abut against the ends of plungers 3a, 3b and the steering action would be controlled by chambers 6a, 6b; the pressure in chamber 6b being controlled by distributor 43. If for any reason the pressure source 3449 should fall to zero, the cylinders 2a and 2b would abut against the end of cylinders 1a and 1b under the pressure in chambers 8a and 8b and the steering action would be controlled by chambers 8a, 8b through the distributor 42.

Thus the above system reduces to a minimum. the time required to switch the steering action from one source of pressure to the other.

In the embodiment in FIG. 3 the jacks A and B are arranged on opposed sides of swing bar 11, the smaller diameter plungers of the jacks being connected to the swing bar 11 at the same point 19a.

A pump 51 is connected by conduits 52 and 53 to the smaller diameter plungers and a pump 54 is connected by conduits 55 and 56 to the cylinders of jack A and B, in manner such that the liquid under pressure for operating the jacks circulates between the jacks in a closed circuit across the pumps 51 and 54. A valve 57 interposed in a conduit 58 permits forming a bypass between the conduits 52 and 53 and a valve 59 interposed in conduit 60 permits forming a bypass between the conduits 55 and 56 in manner to put the pumps 51 and 55 in hydraulic short circuit.

The cylinders of jacks A and B are connected to fixed pivots at G1, 64.

A chain transmission system or the like 71 connects the two pumps 51 and 54 to a rotatable member 72 in manner such that rotary movement of this member brings about a simultaneous rotation of the two pumps. The hydraulic circuits being previously charged with liquid and the two valves 57 and 59 closed, pumps 51 and 54 replenish one of the jacks A and B with as much liquid as they have drawn from the other.

Thus, when the rotary member 72 is turned in a predetermined direction, the valve 59 being opened to place the pump 54 in hydraulic short circuit, the pump 51 operated by the rotary member 72 forces liquid under pressure by way of conduit 52 toward the jack A while drawing liquid from the jack B by way of conduit 53. Thus the plunger of jack A will extend to the right and the plunger of jack B will retract to the right.

The same operation but in opposed direction occurs by turning the rotary member 72 in direction opposed to the foregoing.

In case of breakdown of the circuits 51, 52, 53, circuits 54, 55, 56 may be placed into the operation by closing the valve 59, thus permitting the pump 54 to reestablish the operation described. The pressure chambers provided in the cylinders of jacks A and B to operate with the circuits 54, 55, 56 now come into place, thus assuring the transmission of pressure developed by the pump 54 to the bar 11 with a force greater than that exerted upon the swing bar by the jacks A and B in the course of normal operations, that force being such that it is capable of displacing the bar 11.

With the arrangement of applicant, it is apparent that no cavitation can take place in the chambers of the actuator connected to the inoperative source of pressure due to the fact that the intermediate cylinders 2a, 2b abut against a fixed stop, i.e., either the closed end of cylinders 1a, lb, or the end of plungers 3a, 3b as the case may be, and, therefore, a positive and precise steering is assured.

As many changes could be made in the above constructions and many apparently widely different embodiments of this invention could be made without departing from the scope of the claim, it is intended that all matter contained in the above description or shown in the.

accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

A hydraulic system comprising a first and second source of fluid under pressure, a control member pivotally mounted between its ends, a pair of fluid controlled actuators each comprising a pair of cylinders, one slidably. mounted in the other and defining a plunger, and a second plunger slidably mounted in said first plunger, one end of each of the actuators being pivotally connected to said control member on opposite sides of its pivotal mount, to define two lever arms, one on each side of said pivot, and a pivotal mount for the other end of each actuator, means to elfect fiow of fluid under pressure from either one of said sources into an associated one of the cylinders of each of said actuators for actuation of the plungers thereof, means to provide discharge of fluid from the other cylinder of each actuator, and means to vary the torque tending to rotate said control member in one direction about its pivot and resulting from the force eX- erted by one of said actuators against one of said lever 5 arms with respect to the torque tending to rotate said control member in the opposite direction about its pivot resulting from the force exerted by the other of said actuators against the other of said lever arms, whereby when said torques are equal the control member Will re- 10 main in fixed position.

References Cited in the file of this patent UNITED STATES PATENTS Field et al Feb. 20, Janney Mar. 16, Forman Dec. 11, Campbell May 26, Erling Aug. 14, Willis Oct. 9, Zumbusch Mar. 9, MacDonald Mar. 15, 

